Stuart Chester, who has Down’s syndrome, epilepsy and autism and is unable to feed or wash himself, is being told by officers in the Tory minister’s Department for Work and Pensions to prove he is unfit for work.

The 25-year-old has been sent a controversial 20-page work capability assessment form to fill in that will investigate his fitness for work and whether he deserves his Disability Living Allowance (DLA) and Employment and Support Allowance (ESA) benefits.

Last night Social Justice Secretary Alex Neil described Stuart’s case as “absolutely outrageous” and “shameful”.

Stuart has been given a deadline of September 18 to complete the complicated and detailed document and return it to the DWP.

His mother Deborah McKenzie, 51, said receiving the form had caused her “undue stress” and said Duncan Smith’s plan to deliberately target the sick and disabled was tantamount to “genocide”, after shocking DWP figures were released last week showing more than 80 people were dying each month following work capability assessments.

She said: “Stuart gets the high-rate DLA and he was supposed to get that for life because his condition will never change. He also received ESA benefits.

“I cannot understand why he was sent this capability for work questionnaire because he cannot talk, read or write or do anything for himself. There is no way he could work and this is just causing a lot of undue stress and anxiety.

“I was really upset when the form came through the door. I called up the DWP and asked them why they would send it out to someone like my son when he is supposed to to get DLA for life and they told me it was tough luck, that it’s just the way it is and I would just need to fill out the form for him just like everyone else.

“I know other disabled people in wheelchairs with conditions like cerebral palsy, also people like Stuart who cannot do anything for them, are being harassed by the DWP to fill in fit for work forms when there is absolutely no way they could work.

“I used to have to fill in a form for my son every three years but eventually we were told he had the DLA for life because his circumstances were not going to change and he I no longer had to fill in an application for benefits for him.

“I am his full-time carer and there is no way my son could work, no chance. He needs 24/7 care and cannot feed or wash himself and he has a lot of accidents toilet-wise. I have to do everything for him.”

Neil called for the “cruel” assessments on the sick and disabled to be scrapped, and demanded that David Cameron hand over the rights to decide on benefits to the Scottish Government.

He said: “This is absolutely outrageous and these are the kind of cases which highlight that the Tories are out of control and they must hand over running of our benefits system to the Scottish Government.

“It bad enough the DWP sends out these forms to people like Stuart but they don’t seem to understand the stress and worry this causes families in Scotland.

“If someone is clearly unable to work and has a lifelong condition they should not be hounded like this and they should be left alone, not put through the hell of being assessed for work and worrying about whether or not they will get their benefits when they are quite clearly entitled to them.

“It is nothing but bullying, harassment, intimidation and a breach of human rights of the most vulnerable in our society and it has got to stop.

“They have crossed the line and if we had control over these benefits, the first thing we would put an end to this kind of harassment and treat these people with respect and dignity they deserve.”

Last week, disability campaigners spoke to The National and warned more people would die because of work capability assessments unless they were scrapped.

The claim followed the release of figures that revealed 2,380 claimants died between December 2011 and February 2014 shortly after being told to get back to work and that their benefits were being stopped.

In the same period, 50,580 people who received ESA died within two weeks of their benefit claim ending.

Stephen Cruickshank, director of the Scottish Disability Equality Forum, who has spinal neuropathy, said the work capability assessments were unfit for purpose.

Mother-of-two Deborah, of Glasgow, said Duncan Smith had “a lot to answer for” and described him as “the lowest of the low” for targeting disabled people.

She said: “I don’t know how Iain Duncan Smith can sleep at night or live with himself targeting the disabled and most vulnerable in our society like this.

“It is beyond belief and absolutely disgusting considering many of the people being sent these forms were awarded with DLA for life which we had to fight for.”

Deborah said coping with everyday life caring for Stuart was “hard and challenging” and even though she knows that he cannot work, it is the uncertainty of having to fill in the complicated form that is putting her under even more stress.

A DWP spokesman said: “We regularly review people’s conditions to ensure that they are not simply written off and condemned to a life on benefits. That’s why we have improved the work capability assessment since it was introduced in 2008, ensuring that it is fairer and more accurate.

“Decisions are taken following a thorough independent assessment, and consideration of supporting medical evidence provided to us by a claimant’s GP or medical specialist.”

“It’s important that regular assessments are made, as for some people, conditions may improve or worsen.”